Actuator, unclamp apparatus having actuator, and machining apparatus

ABSTRACT

An actuator includes a power source, a cam member driven by power from the power source, a following member moving in connection with a motion of the cam member, an accommodation chamber accommodating an actuating medium, and a punch cylinder outputting the power transmitted to the actuating medium by the following member.

TECHNICAL FIELD

The present invention relates to an actuator, an unclamp apparatushaving the actuator, and a machining apparatus.

BACKGROUND ART

Conventionally, machining apparatuses such as punching machines areequipped with actuators capable of outputting a large driving force fora brief moment.

Such an actuator includes a hydraulic circuit including, for example, ahydraulic pump connected to an oil tank and driven by a motor, aservovalve connected to a discharge-side pipe of the hydraulic pump, acheck valve, a relief valve, and an accumulator. Then, the above-notedservovalve is connected to a hydraulic cylinder having a piston rodperforming a punching process by striking, and the hydraulic pressuredischarged by the hydraulic pump is sent to an upper chamber of thehydraulic cylinder to move the piston rod down. The piston rod thenprovides a punching process.

Patent Document 1: Japanese Patent Laying-Open No. 2000-312929DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

In the actuator configured in the foregoing manner, however, thehydraulic pump has to be always driven, and in addition, unnecessarypressure has to be released from the relieve valve, resulting in muchuseless energy and poor driving efficiency.

The present invention is made in view of the foregoing problem, and anobject of the present invention is to provide an actuator capable ofoutputting a large driving force for a short time with improved energyefficiency, an unclamp apparatus having this actuator, and a machiningapparatus.

Means for Solving the Problems

An actuator in accordance with the present invention includes: a drivingsource; a cam driven by power from the driving source; a followingmember moving in connection with a motion of the cam: an accommodationchamber accommodating an actuating medium; and an output portionoutputting the power transmitted to the actuating medium by thefollowing member. Preferably, the actuator further includes a connectionportion connected with the above-noted accommodation chamber and theoutput portion. Preferably, the above-noted actuating medium is a liquidactuating medium, and the actuator further includes a separationmechanism connected to an output mechanism to be able to separate gas inthe actuating medium. Preferably, the actuator further includes anauxiliary power source capable of applying auxiliary power to theabove-noted cam member. Preferably, the actuator further includes avalve supplying outside air into the above-noted accommodation chamberand ejecting gas in the accommodation chamber.

An unclamp apparatus in accordance with the present invention includesthe aforementioned actuator. A machining apparatus in accordance withthe present invention includes the aforementioned actuator.

EFFECTS OF THE INVENTION

According to an actuator, an unclamp apparatus and a machining apparatusin accordance with the present invention, a large driving force can beoutput for a short time, and in addition, the driving efficiency can beimproved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view schematically showing a structure of apunching machine having an actuator in accordance with a firstembodiment.

FIG. 2 is a plan view of a cam member.

FIG. 3 is a side view, partially in section, showing a firstmodification of the actuator in accordance with the present embodiment.

FIG. 4 is a schematic diagram showing a second modification of theactuator in accordance with the present embodiment.

FIG. 5 is a cross-sectional view showing an example in which theactuator in accordance with the present embodiment is applied to anunclamp apparatus.

FIG. 6 is a cross-sectional view showing an actuator supplying a drivingforce for an unclamp operation to the unclamp apparatus shown in FIG. 5.

DESCRIPTION OF THE REFERENCE SIGNS

10 power source, 11 auxiliary power mechanism, 12 rotation shaft, 13hydraulic pump, 14 punch cylinder, 15 cam member, 16, 17 cam portion, 18roller member, 19 piston rod, 20 cylinder portion, 20 a accommodationchamber, 21 pressurization chamber, 24 valve, 26 reservoir chamber, 27connection tube, 30 punch rod, 40 gas-liquid separation tank, 50 powertransmission mechanism, 100 actuator, 200 punching machine, 300 unclampapparatus.

BEST MODES FOR CARRYING OUT THE INVENTION

Using FIG. 1 to FIG. 6, an actuator and a machining apparatus inaccordance with the present embodiment will be described. It is notedthat the same structures and corresponding structures are denoted withthe same reference characters and the description thereof may sometimesbe omitted.

FIG. 1 is a cross-sectional view schematically showing a structure of apunching machine 200 having an actuator 100 in accordance with a firstembodiment.

As shown in FIG. 1, punching machine (machining apparatus) 200 includesactuator 100 and, for example, a work holding mechanism holding a work.Actuator 100 includes a power source 10 having a motor, a clutchmechanism, and a speed reduction mechanism, a punch cylinder 14 as anoutput mechanism, and a power transmission mechanism 50 transmittingpower from power source 10 to punch cylinder 14 through oil (actuatingmedium).

Punch cylinder 14 includes a punch rod (drive portion) 30 driven by thepressure of oil supplied from power transmission mechanism 50 to performpunch processing on a work, and a cylinder portion 31 slidablyaccommodating punch rod 30 and having an oil accommodation chamber 32defined therein for accommodating oil from power transmission mechanism50.

Furthermore, this punch cylinder 14 further includes an elastic member33 biasing punch rod 30, and oil supplied into oil accommodation chamber32 causes punch rod 30 to be pushed toward a work against a biasingforce from elastic member 33.

Power transmission mechanism 50 includes a rotation shaft (drive shaft)12 capable of being rotatably driving by power source 10, a cam member15 provided for rotation shaft 12, and a hydraulic pump 13 following themotion of cam member 15 for pressurizing and discharging oil. Then,hydraulic pump 13 includes a piston rod (following member) 19 followingthe motion of cam member 15, and a cylinder portion 20 slidablysupporting piston rod 19.

Cylinder portion 20 has an accommodation chamber 20 a defined thereinfor accommodating oil and has its capacity varied by piston rod 19sliding. Here, accommodation chamber 20 a includes a reservoir chamber26 having a diameter larger than the diameter of piston rod 19, and apressurization chamber 21 connected to a lower end portion of reservoirchamber 26 to have piston rod 19 fitted therein and having oilpressurized by piston rod 19.

Here, in a previous state in which piston rod 19 is fitted inpressurization chamber 21, a gap is formed between an inner wall surfaceof pressurization chamber 21, an inner wall surface of reservoir chamber26, and piston rod 19, so that reservoir chamber 26 is in communicationwith pressurization chamber 21. Then, since reservoir chamber 26 ispositioned above pressurization chamber 21, gas such as the air cominginto pressurization chamber 21 is displaced upward to enter reservoirchamber 26. In other words, the gas in pressurization chamber 21 isejected into reservoir chamber 26, and the gas such as the air ejectedinto reservoir chamber 26 is accumulated on the side of the upper endportion of reservoir chamber 26. In this manner, the air inpressurization chamber 21 is separated, and pressurization chamber 21 isfilled with oil. Here, an annular seal member 23 is provided on an innercircumferential surface of pressurization chamber 21. Then, a lower endportion of piston rod 19 is displaced toward pressurization chamber 21from the state in which it is kept apart from pressurization chamber 21as shown in FIG. 1, and upon reaching seal member 23, pressurizationchamber 21 and reservoir chamber 26 are separated from each other. Then,when piston rod 19 is further displaced downward to enter pressurizationchamber 21, pressurization of oil in pressurization chamber 21 isstarted. Here, as described above, the entrance of gas such as the airinto pressurization chamber 21 is prevented, so that piston rod 19 canpressurize oil well.

Cylinder portion 20 is provided with valves 24, 25 so that a prescribedpressure can be kept in cylinder portion 20 by ejecting the gas incylinder portion 20 to the outside when the internal pressure ofcylinder portion 20 is a prescribed pressure or higher or by supplyingthe outside air to the inside when the interior of cylinder portion 20reaches a prescribed pressure or lower. It is noted that valves 24, 25are positioned above the level of oil.

A roller member 18 is provided at an end portion of piston rod 19 on thecam member 15 side. A shaft portion 18 a rotatably supporting rollermember 18 is inserted in a hole portion formed on the upper end portionside of piston rod 19. Then, roller member 18 is in contact with anouter circumferential surface of cam member 15. Therefore, rotation ofcam member 15 allows piston rod 19 to slide in accordance with themotion of cam member 15 via roller member 18.

Piston rod 19 slides such that the accommodating capacity ofaccommodating oil in cylinder portion 20 is reduced, whereby oil incylinder portion 20 is pressurized. Then, a connection tube 27 connectedwith cylinder portion 20 and cylinder portion 31 is provided so that oilpressurized by piston rod 19 is supplied into oil accommodating chamber32 of cylinder portion 31 through connection tube 27. In this manner,punch rod 30 is driven by the power transmitted to oil by piston rod 19.In this way, in this actuator 100, the supply amount of oil supplied topunch cylinder 14 can be controlled according to the shape of cam member15.

FIG. 2 is a plan view of cam member 15. As shown in FIG. 1 and FIG. 2,cam member 15 includes a cam portion 16 and a cam portion 17. Then, inthe state shown in FIG. 2, punch rod 30 is retracted from a work, andpiston rod 19 is displaced upward, as shown in FIG. 1.

Then, in FIG. 2, when rotation shaft 12 rotates around a rotation centerline O and can member 15 rotates, roller member 18 is graduallydisplaced downward. In other words, when rotation shaft 12 startsrotation, roller member 18 is in contact at a position P1 which is theclosest from rotation center line O of rotation shaft 12, of thecircumferential surface of cam portion 16.

Then, as cam member 15 rotates, the distance between a contact point atwhich roller member 18 is in contact with cam portion 16 and rotationcenter line O increases.

Therefore, in FIG. 1, piston rod 19 is also displaced graduallydownward. Then, in FIG. 1, the downward displacement of piston rod 19allows the lower end portion of piston rod 19 to enter pressurizationchamber 21 so that oil in pressurization chamber 21 starts beingpressurized.

Then, the oil is supplied to punch cylinder 14 through connection tube27 so that punch rod 30 starts moving.

Furthermore, in FIG. 2, when rotation shaft 12 rotates, the contactpoint between roller member 18 and the outer circumferential surface ofcam portion 16 comes closer to a position P2 which is the most distantfrom rotation center line O, of the outer circumferential surface of camportion 16.

Here, the radius of curvature of the circumferential surface of camportion 16 is formed to increase from position P1 to position P2. Then,the changing rate of radius of curvature in proximity to position P2 issmaller than the changing rate of radius of curvature in proximity toposition P1. In other words, the distance between the circumferentialsurface of cam portion 16 and rotation center line O is formed toincrease from position P1 to position P2, and the changing rate inproximity to position P2 is formed to be smaller than the changing ratein proximity to position P1.

Therefore, in the process during which the contact position betweenroller member 18 and cam portion 16 starts moving from position P1 toposition P2, the displacement speed of roller member 18 is increased,and as the contact position between roller member 18 and cam portion 16comes closer to position P2, the displacement speed of roller member 18is decreased.

In this manner, since the displacement amount of roller member 18 isreduced as the contact position between roller member 18 and cam portion16 comes closer to position P2, can member 15 can be rotated reliablyeven in a state in which a large pressing force is exerted from rollermember 18. Therefore, even when a large pressing force is exerted onroller member 18, such as when punch rod 30 performs punch processing ona work, cam member 15 can rotate thereby to displace roller member 18.Accordingly, punch rod 30 can machine a work reliably.

In this manner, the shape of cam portion 16 of cam member 15 allows thedisplacement speed to become higher when punch rod 30 approaches a work,and also allows a large driving force to be generated reliably whenpunch rod 30 machines a work.

Furthermore, the period during which this actuator 100 is driven islimited to the time when punch cylinder 14 is driven. This preventspower source 10 and power transmission mechanism 50 from being drivenall the time and also eliminates the need for relieving oil into an oiltank or the like, thereby preventing useless energy and in additionimproving the operation efficiency.

Moreover, the driving of punch rod 30 can be varied by varying the shapeof cam member 15, thereby facilitating adaptation to a design change ofproducts.

Then, since the liquid oil transmits the power from power source 10 topunch cylinder 14, the layout of punch cylinder 14 and power source 10and power transmission mechanism 50 can be changed freely by changing anarrangement position of connection tube 27 as appropriate. Thisfacilitates adaptation to a die change due to a design change ofworkpieces.

Here, in actuator 100 in accordance with the present embodiment, asshown in FIG. 1, an auxiliary power mechanism (auxiliary power source)11 is provided which can add auxiliary power to cam member 15. As thisauxiliary power mechanism 11, for example, a coil spring (elasticmember) 38 as shown in FIG. 1 or a gas spring may be employed.

Auxiliary power mechanism 11 includes coil spring 38, a housing case 39housing coil spring 38, a roller member 35 in abutment with acircumferential surface of cam portion 17 of cam member 15, and asupport member 37 rotatably supporting roller member 35 and being biasedtoward cam member 15 by coil spring 38.

A shaft portion 35 a of roller member 35 is inserted into a through holeformed in support member 37. Then, this roller member 35 is pressedagainst the circumferential surface of cam portion 17 by the biasingforce from coil spring 38 via support member 37.

Then, in FIG. 2, cam member 15 pivots in a rotation direction P and whenthe contact position between roller member 18 and the circumferentialsurface of cam portion 16 is in the vicinity of position P2, the forcecomponent of the pressing force applied by roller member 35 to thecircumferential surface of cam portion 17 presses the circumferentialsurface of cam portion 17 in rotation direction P.

In other words, when roller member 18 is in the vicinity of position P2of cam portion 16, the pressing force of roller member 35 pressing thecircumferential surface of cam portion 17 assists cam member 15 torotate in rotation direction P.

Therefore, the powers from power source 10 and auxiliary power mechanism11 are applied to roller member 18. Thus, for example, when a largedriving force needs to be applied to punch rod 30 such as when punch rod30 machines a work, it is possible to prevent the output from powersource 10 from becoming excessively large. This can reduce the maximumoutput required by power source 10 thereby reducing the size and costsof power source 10.

When punch rod 30 machines a work and thereafter retracts from the work,the contact position between roller member 18 and the circumferentialsurface of cam portion 16 passes through position P2 of cam portion 16and is displaced toward position P1.

At that moment, the pressing force applied from roller member 35 to thecircumferential surface of cam portion 17 may act to rotate cam member15 in the direction opposite to rotation direction P. However, since theoutput from power source 10 is larger than the output from auxiliarypower mechanism 11, cam member 15 rotates in rotation direction P.

Then, the contact position between roller member 18 and thecircumferential surface of cam portion 16 is positioned at position P1,so that punch rod 30 returns to the initial position where it isretracted from the work.

FIG. 3 is a side view, partially in section, showing a firstmodification of actuator 100 in accordance with the present embodiment.As shown in FIG. 3, in this actuator 100A, accommodation chamber 20 a ofcylinder portion 20 is filled with oil, and at the upper end ofaccommodation chamber 20 a, a gas-liquid separation tank (separationmechanism) 40 separating gas in the oil is connected through aconnection tube 41.

This gas-liquid separation tank 40 is arranged above cylinder portion20, and in this gas-liquid separation tank 40, the level of oil ispositioned and oil and the air (gas) are filled.

Here, in a state in which piston rod 19 is spaced apart frompressurization chamber 21 as shown in FIG. 3, pressurization chamber 21and reservoir chamber 26 are in communication with each other.Furthermore, reservoir chamber 26 and gas-liquid separation tank 40 arein communication with each other through connection tube 41 connected toreservoir chamber 26, so that pressurization chamber 21, reservoirchamber 26, and gas-liquid separation tank 40 communicate with eachother.

Therefore, gas such as the air entering pressurization chamber 21 isejected to gas-liquid separation tank 40 through reservoir chamber 26and connection tube 41.

Then, when the lower end portion of piston rod 19 enters pressurizationchamber 21 and reaches seal member 23, an opening portion ofpressurization chamber 21 is closed by piston rod 19, so thatpressurization chamber 21 is separated from reservoir chamber 26. Then,piston rod 19 further enters pressurization chamber 21, whereby the oilin pressurization chamber 21 is pressurized. At this moment, the air inpressurization chamber 21 has already been ejected to gas-liquidseparation tank 40, so that piston rod 19 can pressurize the oil well toallow power to be transmitted well to punch rod 30.

FIG. 4 is a schematic view showing a second embodiment of the actuatorin accordance with the present embodiment. As in the example shown inFIG. 4, the power from power source 10 may be supplied to hydraulic pump13 through an end cam (bell cam) 115.

FIG. 5 is a cross-sectional view showing an example in which theactuator in accordance with the present embodiment is applied to anunclamp apparatus 300, and FIG. 6 is a cross-sectional view showing anactuator 500 supplying a driving force for an unclamp operation tounclamp apparatus 300 shown in FIG. 5.

In FIG. 5, unclamp apparatus 300 includes a casing 151, a main shaft 152rotatably supported on casing 151, an attachment portion 154 provided ata lower end portion of main shaft 152 and having a tool 170 attachedthereto, and a driving source 400 such as a motor rotating main shaft152. Main shaft 152 rotates with tool 170 attached to attachment portion154, whereby a not-shown work is machined. It is noted that main shaft152 is rotatably supported by a plurality of bearings 156, 157.

Unclamp apparatus 300 further includes a drawbar 153 inserted in athrough hole 152 a formed in main shaft 152 to extend in the axialdirection, an elastic member 155 such as a Belleville springaccommodated in through hole 152 a to bias drawbar 153 in the directionaway from attachment portion 154, an unclamp mechanism 114 capable ofpressing drawbar 153 toward attachment portion 154, and a collet (gripportion) 161.

Collet 161 is accommodated in through hole 152 a and is engaged withboth of an upper end portion of tool 170 attached to attachment portion154 and a lower end portion of drawbar 153. Then, when tool 170 isattached to attachment portion 154, drawbar 153 is biased upward byelastic member 155 and collet 161 is also biased upward.

Therefore, tool 170 is attracted toward main shaft 152 by collet 161,and tool 170 is fitted in attachment portion 154.

Then, unclamp apparatus 300 includes actuator 500 for bringing tool 170attached (clamped) to attachment portion 154 into an unclamp state, asshown in FIG. 5 and FIG. 6.

This actuator 500 is structured similarly to the aforementioned actuator100 shown in FIG. 1. Actuator 500 includes power source 10, unclampmechanism 114 as an output portion shown in FIG. 5, and powertransmission mechanism 50 transmitting power from power source 10 tounclamp mechanism 114.

Here, connection tube 27 through which oil circulates is connectedbetween power transmission mechanism 50 and unclamp mechanism 114.Therefore, by changing a manner of routing connection tube 27, powersource 10, power transmission mechanism 50, and the like can be arrangedat a position distant from the unclamp apparatus body. In addition, theposition of actuator 500 can be changed as necessary according to theinstallation condition of unclamp apparatus 300.

In FIG. 5, unclamp apparatus 114 includes an unclamp cylinder 160 drivenby hydraulic pressure supplied from power transmission mechanism 50, apress member 150 pressed by a piston rod 130 of unclamp cylinder 160,and a pin 133 engaged with press member 150 and drawbar 153. In theclamp state, pin 133 is fixed to press member 150, inserted in a throughhole formed around the circumferential surface of main shaft 152, andpositioned above drawbar 153.

Unclamp cylinder 160 includes piston rod 130 being slid by hydraulicpressure supplied from power transmission mechanism 50, a cylinderportion 131 slidably supporting piston rod 130, and an oil accommodationchamber 132 defined in cylinder portion 131 and supplied with oil.

Then, in order to bring tool 170 into the unclamp state, first, in FIG.5, power source 10 is actuated to rotate cam member 15.

Here, cam member 15 is formed in the shape as shown in FIG. 2 above, andin a state in which tool 170 is clamped, roller member 18 is in contactwith the circumferential surface of cam portion 16 at position P1 of camportion 16.

Then, cam member 15 rotates, and as the contact position between rollermember 18 and the circumferential surface of cam portion 16 comes closerto position P2, the distance between rotation center line O and thecontact position between roller member 18 and cam portion 16 increases.

Accordingly, piston rod 19 is displaced so that piston rod 19 reducesthe capacity of accommodation chamber 20 a.

Then, piston rod 19 enters pressurization chamber 21 whereby oil ispressurized and then supplied to oil accommodation chamber 132 shown inFIG. 6. Thus, piston rod 130 is displaced toward tool 170 and pressmember 150 and pin 133 are also displaced toward tool 170. Pin 133 isdisplaced toward tool 170 thereby being brought into abutment with theupper end portion of drawbar 153 and pressing drawbar 153 toward tool170.

Accordingly, drawbar 153 starts being displaced toward tool 170 againstthe biasing force from elastic member 155. Then, when drawbar 153 isdisplaced downward to a prescribed position, collet 161 is deformed andthe engagement state between collet 161 and tool 170 is then released.

Then, in FIG. 2, when the contact position between roller member 18 andcam portion 16 reaches the proximity of position P2 and position P2, alarge power from power transmission mechanism 50 is supplied to unclampcylinder 160.

Then, a large driving force from power transmission mechanism 50 istransmitted to drawbar 153 through piston rod 130, press member 150, andpin 133. This ensures that tool 170 is removed from attachment portion154. In this manner, the unclamp operation of a tool is finished. It isnoted that auxiliary power mechanism 11 is also provided in the exampleshown in FIG. 6 in order to reduce the maximum output of power source10.

It is noted that upon completion of the unclamp operation, the drivingof power source 10 shown in FIG. 6 is stopped and a clutch mechanism inpower source 10 disconnects power transmission to rotation shaft 12.Accordingly, the unclamp state of tool 170 is maintained. When the toolis unclamped in this manner and another tool is thereafter attached, anew tool 170 is inserted in attachment portion 154.

When the inserted tool 170 is thereafter clamped, power source 10 shownin FIG. 6 is actuated again and the clutch mechanism in power source 10connects power transmission to rotation shaft 12.

Accordingly, cam member 15 starts rotating. At this moment, in FIG. 2,the contact position between roller member 18 and cam portion 16 isdisplaced from position P2 toward position P1.

Therefore, the distance between the contact position between rollermember 18 and cam portion 16 and rotation center line O is decreased.Accordingly, in FIG. 6, piston rod 19 is displaced upward so thathydraulic pressure is reduced and in addition the oil starts returninginto accommodation chamber 20 a of cylinder portion 20.

Then, in FIG. 5, piston rod 130 is also displaced to reduce the capacityof oil accommodation chamber 132 and starts being displaced in thedirection away from attachment portion 154.

When the driving force applied from unclamp mechanism 114 to drawbar 153is reduced in this manner, drawbar 153 starts being displaced upward bythe biasing force from elastic member 155.

As drawbar 153 is displaced upward, collet 161 provided at the lower endportion of drawbar 153 is also displaced apart from attachment portion154.

As collet 161 is displaced in this manner, the end portion of collet161, which has been deformed to be opened, is deformed to be closed tocome into engagement with the upper end portion of tool 170.

Then, drawbar 153 is further displaced upward, so that collet 161engaged with the lower end portion of drawbar 153 and tool 170 engagedwith collet 161 are also displaced upward.

In this manner, new tool 170 is attached to attachment portion 154.

Although the embodiment of the present invention has been describedabove, it should be understood that the embodiment disclosed herein isillustrative rather than limitative in all respects. The scope of thepresent invention is shown in the claims, and it is intended that allthe modifications within the claims and the equivalencies to the claimsshould be embraced.

INDUSTRIAL APPLICABILITY

The present invention is suitable for an actuator, an unclamp apparatushaving an actuator, and a machining apparatus.

1. An actuator comprising: a driving source; a cam driven by power fromsaid driving source; a following member moving in connection with amotion of said cam; an accommodation chamber accommodating an actuatingmedium; and an output portion outputting the power transmitted to saidactuating medium by said following member.
 2. The actuator according toclaim 1, further comprising a connection portion connected with saidaccommodation chamber and said output portion.
 3. The actuator accordingto claim 1, wherein said actuating medium is a liquid actuating medium,and the actuator further comprises a separation mechanism connected tosaid output portion to be able to separate gas in said actuating medium.4. The actuator according to claim 1, further comprising an auxiliarypower source capable of applying auxiliary power to said cam member. 5.The actuator according to claim 1, further comprising a valve supplyingoutside air into said accommodation chamber and ejecting gas in saidaccommodation chamber.
 6. An unclamp apparatus comprising the actuatoraccording to claim
 1. 7. A machining apparatus comprising the actuatoraccording to claim 1.